The present invention relates generally to measuring and testing methods and instruments. Stated more particularly, this patent discloses and protects a system and method for monitoring conditions within a container, such as the thickness and position of scum and sludge layers within a septic tank.
As one knowledgeable in the art will be well aware, a typical septic system is founded on a tank in which wastes are collected, settled, and partially digested. The septic tank leeches what is termed gray water into a drain field where it is dispersed. When the system is operating properly, the dispersed gray water will be substantially devoid of solid matter. When the system is not operating properly and solids are suspended in the gray water, the drainage field can become clogged by solids such that the gray water ceases to be absorbed and dispersed properly thereby resulting in drainage field failure. With this, ground and surface water can become polluted, and the system can otherwise malfunction.
When operational, a septic tank has three biologically active zones that are commonly referred to as an upper, cake or scum layer, a middle, liquid zone, and a bottom, sedimentary or sludge layer. Waste matter enters the liquid zone at the middle of the tank. The sedimentary layer is formed as heavy solids settle to the bottom of the tank as sediment, or sludge, where they are further decomposed. Some of the sediment, however, will not be biodegradable and will remain at the bottom of the tank. The cake layer is formed as fats and other lighter suspended solids rise to the top of the tank where they too may further decompose.
During proper septic tank operation, only material from the liquid zone is dispensed to the drainage field. The effective volume and rate of flow of the tank determine the tank""s settlement rate. The volume of the tank""s liquid zone, therefore, is considered the tank""s effective volume. In turn, that effective volume is used to determine the fixed design capacity of the tank, which is measured as the ability of the tank to process a particular flow rate of material. With this, the tank will be unable to process material entering the system at an inflow rate over the maximum allowable flow rate.
A septic tank""s system capacity, on the other hand, is condition dependent in that it is indicative of the system""s ability to continue to process material. The tank""s system capacity falls to zero when, for example, particles of the sedimentary or cake layers begin to escape from the tank to the drainage field or the sedimentary and cake layers become so close to one another that the liquid layer is nearly or completely extinguished.
Advantageously, as a result of anaerobic decomposition in the upper and bottom layers, the increase in thickness of the sedimentary and cake layers is substantially less than the rate at which corresponding solids are input into the system. Nonetheless, the bottom, sedimentary or sludge layer and the upper, scum or cake layer do tend to increase progressively in thickness during normal operation of the septic system such that the accumulated solids must eventually be pumped from the system.
Common practice suggests that this pumping be carried out when the volume of the middle liquid zone is reduced to roughly one-third of the total height of the three layers. When that need for pumping will be reached, however, is dependent on the mix and overall volume of waste that is input to the system and the effectiveness of the biological decomposition occurring in the septic tank.
Pumping may be considered necessary based on the absolute location of the top layer, the absolute location of the bottom layer, or a combination of these factors that have reduced the volume of the middle, liquid zone to a given extent. Notably, as the volumes of solids increase in the septic tank, the effectiveness of the biological decomposition tends to increase thereby leading to a decreased rate of accumulation even with a constant input rate. With this, it will be appreciated that the required pumping interval is substantially unpredictable and can range from as little as two years to as much as fifteen years and longer.
A major difficulty in septic tank operation is that, because it is necessarily carried out underground, the status of the septic tank is generally difficult or impossible to perceive. With this, the first indication of a failure in the system often comes in the form of the unpleasant backup of waste material into the associated home or building. Even more disadvantageously, this backup occurs typically well after the system has begun to discharge substantial solids into the drainage field.
Advantageously, a number of methods and systems have been disclosed by the prior art for providing an indication as to whether a given septic system is in need of pumping. One most basic means is by digging up and removing the access cover for the tank and dipping what is termed a flapper stick into the tank to gain an estimation of the height of each of the layers. As one will appreciate, this is a cumbersome and unpleasant practice and is often done merely to confirm that an already-occurring failure is in fact due to a need for pumping.
Other systems have been disclosed that are intended to allow a septic tank operator to monitor the contents of the tank without the need for manually opening the tank and interacting with its contents. For example, relatively simple mechanical devices have been disclosed wherein, for example, a float within the tank is coupled to an arm that projects from the tank to indicate the status of one or more layers within the tank. Other, more complex systems have been disclosed with elongate sensing probes for being permanently disposed in a septic tank. Sensors disposed along the probes have been of a wide variety of types including sonic sensors, light emitting and detecting sensor combinations, electrical resistance sensors, and still other sensor arrangements.
Unfortunately, even these improved systems and arrangements have left septic tank operators with a number of disadvantages and shortcomings. By way of example and not limitation, one knowledgeable in the art will be aware that many prior art systems are vulnerable to malfunction and fouling as they spend years disposed within a septic tank. Furthermore, prior art systems often are incapable of providing the septic tank operator with consistently accurate information regarding the status of the contents of the septic tank. Still further, some systems are simply incapable of taking accurate readings or readings of sufficient resolution while others additionally or alternatively cannot relay taken readings accurately or with sufficient resolution from the system to the operator. In light of these and further disadvantages of the prior art, it becomes clear that there remains a need for a septic tank monitoring system and method that overcomes these and other shortcomings of the prior art while providing a number of heretofore unrealized advantages thereover.
Advantageously, the present invention has as its primary object the provision of a system and method for monitoring the condition of stratified layers in a container, such as a septic tank, that meets each of the needs that the prior art has left unmet while providing a number of further advantages thereover.
More particularly, a most basic object of the present invention is to provide a septic tank monitoring system that can function accurately in distinguishing between and identify the location of a sedimentary layer, a scum layer, and any intervening liquid zone in a septic tank.
Another fundamental object of the invention is to provide a septic tank monitoring system that can operate consistently and without malfunction over extended time periods by resisting fouling and similar negative effects.
Yet another object of certain embodiments of the invention is to provide a septic tank monitoring system that can be readily installed relative to a septic tank without a need for tools or attachment hardware.
Still another object of particular embodiments of the invention is to provide a septic tank monitoring system that relays information regarding the status of the septic tank to a septic tank operator in a clear and readily understood format.
These and ftirther objects and advantages will become obvious not only to one who reviews the present specification and drawings but also to one who has an opportunity to make use of an embodiment of the present invention for a septic tank monitoring system.
In carrying forth the foregoing objects, one embodiment of the monitoring system comprises a septic tank monitoring system that distinguishes between and identifies the location of a sedimentary layer, a scum layer, and any intervening liquid zone in a septic tank by incorporating an elongate sensing probe for being disposed in the septic tank, a plurality of sensors disposed along the sensing probe each including a means for providing a signal that enables a determination of whether the sensor is disposed proximal to the sedimentary layer, the scum layer, or any intervening liquid zone in the septic tank, and a remote monitor operably associated with the plurality of sensors for providing a remote indication of the location of the sedimentary layer, the scum layer, and any intervening liquid zone in the septic tank based on the signals from the plurality of sensors. Under even this basic arrangement, the septic tank monitoring system advantageously enables a septic tank operator to monitor the contents and condition of the septic tank without a need for excavating and physically inspecting the septic tank.
The elongate sensing probe could, for example, comprise an elongate tube. A retaining member can be slidably associated with the elongate tube and biased toward an extended position so that the sensing probe can be inserted into and retained in the septic tank by compressing the retaining member, orienting the elongate sensing probe preferably generally vertically in the septic tank, and allowing the retaining member to decompress. With this, the sensing probe can be frictionally retained in the septic tank with the first end of the elongate sensing probe frictionally engaging a first boundary of the septic tank, such as the top of the tank, and the second end of the elongate sensing probe frictionally engaging a second boundary of the septic tank, such as the bottom of the tank.
To prevent damage to the components housed therein, the elongate tube preferably will be sealed to prevent liquids and solids from entering the elongate tube from the septic tank. The retaining member can be tubular and can retain the biasing means therewithin, and it too can be sealed to prevent the entry of liquids and solids. Even more preferably, the first and second ends of the sensing probe can have at least one point, such as by being conical, for positively engaging the boundaries of the septic tank.
The sensors could be of a variety of types, each well within the scope of the present invention.
In preferred embodiments, some or all of the sensors could be hemispherical sensor electrodes while, in other embodiments, some or all sensors could comprise ring electrodes. One of the sensors can preferably be employed as a references sensor and can be disposed on the elongate tube to coincide in location with a lower end of an outlet baffle of the septic tank. With this, the locations of the remaining sensors and the material disposed in proximity thereto can be measured based on their distance from the reference sensor.
A tank electronics unit can be coupled to the elongate sensing probe and operably associated with the remote monitor by, for example, an interconnecting cable or any other means, and each of the plurality of sensors can be electrically coupled to the tank electronics unit. Where an interconnecting cable is employed, a cover plate can be provided for being disposed over the interconnecting cable as it exits the septic tank for shielding the interconnecting cable from damage during excavation and the like.
A microcontroller can be operably associated with each of the plurality of sensors for providing them with a high frequency, preferably 10 KHz, alternating current flow. A multiplexer and a synchronous demodulator can be incorporated for multiplexing and demodulating analog voltage signals produced by the current flow to each sensor. Even further, an analog to digital converter can be employed for converting the voltage signals from analog to digital. Also, a means for processing and analyzing each digital voltage signal can be incorporated to determine for each sensor whether the material disposed in proximity thereto is the sedimentary layer, the scum layer, or any liquid zone that may be therebetween.
Preferred embodiments will also include means operably associated with the remote monitor for displaying information representative of whether the material disposed in proximity to each sensor is within the sedimentary layer, the scum layer, or any liquid zone. The means for displaying information can be a visual indicator representative of each sensor, and the visual indicators can be disposed in order corresponding to a location of each sensor along the elongate sensing probe. The means for displaying information and the means for processing and analyzing can cooperate to activate each visual indicator that is disposed adjacent to any liquid zone that is in the septic tank while leaving inactive each visual indicator that is disposed adjacent to either the sedimentary layer or the scum layer. Even more preferably, a distance legend can be disposed adjacent to the visual indicators to denote the distance of the corresponding sensor from the reference sensor, and a thickness legend can be disposed adjacent to the visual indicators to denote the thickness of the sedimentary layer and the scum layer in the septic tank.
It should be appreciated that the remote monitor could comprise a specially designed and constructed device, or it could comprise a personal computer system in cooperation with specially designed software. Even further, where there is a dedicated remote monitor, it can include a data interface connector for enabling a coupling to an external device, such as a personal computer. In any event, the monitoring system can include a flood alarm indicator operably associated with the remote monitor for indicating an abnormally high material level in the septic tank, and a pump-out warning indicator can be operably associated with the remote monitor for alerting a septic tank operator to a need for pumping out material within the septic tank.
It should be understood that, although the present invention is primarily described herein as a system for monitoring the conditions of a septic tank, the invention can find equally advantageous application relative to other materials, possibly disposed in stratified layers, in other containers. Furthermore, one will appreciate that the foregoing discussion broadly outlines the more important features of the invention to enable a better understanding of the detailed description that follows and to instill a better appreciation of the inventor""s contribution to the art. Before an embodiment of the invention is explained in detail, it must be made clear that the following details of construction, descriptions of geometry, and illustrations of inventive concepts are mere examples of the many possible manifestations of the invention.